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i965: Fix negate with unsigned integers

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For code such as:

uint tmp1 = uint(in0);
uint tmp2 = -tmp1;
float out0 = float(tmp2);

We produce code like:
mov(8)    g5<1>.xF    -g9<4,4,1>.xUD

which does not produce correct results. This code produces the
results we would expect if tmp1 and tmp2 were signed integers
instead.

It seems that a similar problem was detected and addressed when
using negations with unsigned integers as part of condionals, but
it looks like the problem has a wider impact than that.

This patch fixes the problem by preventing copy-propagation of
negated UD registers in all scenarios, not only in conditionals.

Fixes the following 24 dEQP tests:

dEQP-GLES3.functional.shaders.operator.unary_operator.minus.*_uint_*
dEQP-GLES3.functional.shaders.operator.unary_operator.minus.*_uvec2_*
dEQP-GLES3.functional.shaders.operator.unary_operator.minus.*_uvec3_*
dEQP-GLES3.functional.shaders.operator.unary_operator.minus.*_uvec4_*

Reviewed-by: Anuj Phogat <anuj.phogat@gmail.com>
This commit is contained in:
Iago Toral Quiroga 2015-01-19 12:32:09 +01:00
parent 5b941ce857
commit 6dd346c232
2 changed files with 10 additions and 8 deletions
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9
src/mesa/drivers/dri/i965/brw_fs_copy_propagation.cpp
View file

@ -302,9 +302,12 @@ fs_visitor::try_copy_propagate(fs_inst *inst, int arg, acp_entry *entry)
(entry->dst.reg_offset + entry->regs_written) * 32)
return false;
/* See resolve_ud_negate() and comment in brw_fs_emit.cpp. */
if (inst->conditional_mod &&
inst->src[arg].type == BRW_REGISTER_TYPE_UD &&
/* we can't generally copy-propagate UD negations because we
* can end up accessing the resulting values as signed integers
* instead. See also resolve_ud_negate() and comment in
* fs_generator::generate_code.
*/
if (inst->src[arg].type == BRW_REGISTER_TYPE_UD &&
entry->src.negate)
return false;

9
src/mesa/drivers/dri/i965/brw_vec4_copy_propagation.cpp
View file

@ -314,12 +314,11 @@ try_copy_propagate(struct brw_context *brw, vec4_instruction *inst,
if (inst->is_send_from_grf())
return false;
/* We can't copy-propagate a UD negation into a condmod
* instruction, because the condmod ends up looking at the 33-bit
* signed accumulator value instead of the 32-bit value we wanted
/* we can't generally copy-propagate UD negations becuse we
* end up accessing the resulting values as signed integers
* instead. See also resolve_ud_negate().
*/
if (inst->conditional_mod &&
value.negate &&
if (value.negate &&
value.type == BRW_REGISTER_TYPE_UD)
return false;